Pavement marking systems that have been described in the patent literature or are commercially available include solvent-borne and water-borne paints, preformed adhesive tapes, preformed thermoplastic tapes, two-part reactive thermoset systems (e.g., epoxies and acrylates), hopper-borne molten thermoplastic systems and combustion flame-sprayed thermoplastic powder systems. The flame-sprayed thermoplastic systems are especially quick and easy to apply (even on roughened or cracked surfaces or under extreme low temperatures) and have relatively low cost. However, existing commercially-available flame-sprayed systems appear to be less durable than some commercially-available alternatives such as preformed tapes, and consequently may require more frequent replacement and greater long-term installation labor expense.
Aznar, A. C., Caprari, J. J., Meda, J. F., and Slutzky, O., "Study of Formulation Variables of Thermoplastic Reflecting Materials for Traffic Marking", Journal of Coatings Technology, 69, 868, pp. 33-38 (May 1997) describe typical thermoplastic pavement marking materials and their wear resistance using wet and dry Taber abrasion tests.
Andrady, A. L., "National Cooperative Highway Research Program Report 392, Pavement Marking Materials: Assessing Environment-Friendly Performance", Washington, D.C. (1997) describes several types of pavement marking materials, including typical formulations for commercially available pavement markings (see pp. 9-13 and 52-57).
U.S. Pat. No. 3,410,185 (Harrington '185), U.S. Pat. No. 3,664,242 (Harrington et al. '242), U.S. Pat. No. 3,849,351 (Jorgansen), U.S. Pat. No. 3,914,468 (Condon et al.), and U.S. Pat. No.4,058,641 (Hnojewyj), and the brochures entitled "Green Lite.TM. Striping Powder and GLG-20 System" (publication 75-0299-7023-5) and "Green Lite.TM. Striping Powder" (publication 75-0299-7789-1 (120.5)ii) describe machines and compositions for use in flame-spray pavement marking applications.
Japanese published patent application (Kokai) No. HEI 9 [1997]-314032 describes flame-sprayable coatings for use on flood gates, valves and water pipes, liners, vanes and gates and other substrates but does not describe the use of such materials as pavement markings. An "acrylic type resin powder" and more specifically an "ethylene acryl acetate" is said to be employed, together with an alumina filler material.
The brochures entitled "The 124 System" and "Put on a PFS Coat" from Plastic Flamecoat Systems describe a handheld flame-spray applicator that can be used, inter alia, to line the interior of a pothole, and to seal and repair cracks, during asphalt repair procedures.
The brochure entitled "Elvaloy.RTM. AM" (publication H-37622) describes a reactive asphalt additive said to be an ethylene/glycidyl/acrylate terpolymer.
U.S. Patent No. 3,011,412 (Harrington et al. '412) describes a urea-based meltable temporary protective coating for thermoset or thermoplastic pavement marking paints.
Japanese patent (Kokoku) No. HEI 5[1993] - 33661 describes a preformed pavement marking tape made from a molded sheet containing a binder including an "ethylene methacrylic acid copolymer resin with 10 to 15 weight % methacrylic acid content", and bonded to pavement using a hot-melt adhesive which had been preapplied to the tape before use. No mention is made of flame-spraying the copolymer or the sheet ingredients onto pavement.
U.S. Pat. No. 4,069,281 (Eigenmann), U.S. Pat. No. 4,388,359 (Ethen et al.), U.S. Pat. No. 4,490,432 (Jordan), U.S. Pat. No.5,127,973 (Sengupta et al.), U.S. Pat. No. 5,194, 13 (Lasch et al. '113), U.S. Pat. No.5,374,465 (Fulcomer) and U.S. Pat. No. 5,536,569 (Lasch et al. '560) describe various preformed pavement marking materials which typically have one or more layers in the form of a primer, pressure sensitive adhesive or conformance material between the marker and the pavement.